AB1163 INVESTIGATION OF SELECTED AUTOANTIBODIES IN PSORIATIC ARTHRITIS AND THEIR ASSOCIATION WITH COMORBIDITIES
Authors: A. K. Inderthal, A. Knothe, K. Frommer, C. Heck, M. Arnold, I. Tarner, W. Hermann, C. F. Meneses Villalba, U. Müller-Ladner, R. Hasseli, E. Neumann
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Psoriatic arthritis (PsA) is a chronic inflammatory joint disease. It can result in severe joint destruction and cardiac or pulmonary involvement. So far, no specific autoantibodies have been identified that would simplify the diagnosis of PsA. HLA-B27 positivity is only detectable in 20% of PsA patients. It still takes several years until a diagnosis is established, which is crucial for the treatment. In addition, the disease is associated with a higher body mass index (BMI) and cardiovascular risk. <h3>Objectives</h3> The aim of the study was to identify possible PsA-associated autoantibodies which might enable earlier diagnosis, and to investigate possible associations of these selected autoantibodies with specific comorbidities. <h3>Methods</h3> Both, PsA patients and healthy individuals without known autoimmune disease were included in the study. Sociodemographic data (age, sex, BMI, waist circumference), current disease activity, current rheumatological therapy, cardiovascular diseases and fatigue were investigated. HLA-B27 status was determined and a radiological evaluation of PsA-typical changes in the hands and feet was performed. Serologically, antibodies against ADAMTSL-5, LL37, calpastatin and gliadin were investigated by ELISA. <h3>Results</h3> A total of 107 PsA patients (60% female) and 19 healthy controls (HC) were included. Median age of PsA patients was 59 years (21-80 years), 28% were HLA-B27 positive. Median BMI was 28 kg/m2 (19-48 kg/m2). Cardiovascular disease was present in 65% of patients, which included the following conditions: arterial hypertension, atherosclerosis, heart failure, coronary heart disease (CHD) and myocardial infarction. Antibodies to LL37 were present in 47% of patients compared to 30% of healthy individuals. Antibodies to ADAMTSL-5 were detectable in 47% of patients and 35% of healthy individuals. Calpastatin antibodies were present in 23% of patients and 11% of healthy individuals and against gliadin in 3% of patients and 5% of healthy individuals. In patients with antibodies against LL37, antibodies against ADAMSTL-5 could also be detected in most cases (p&lt; 0.001). In patients with a treatment duration of &lt;5 years more frequently antibodies against calpastatin were detectable compared to those with longer treatment duration (p&lt;0.05). <h3>Conclusion</h3> In summary, none of the antibodies investigated were found to be significantly elevated in PsA-patients compared to HC. However, in the group of patients with a treatment duration &lt;5 years, autoantibodies against calpastatin were detected more frequently. This could suggest that this autoantibody might play a role in the early phase of PsA and immunomodulatory treatment might diminish autoantibody levels. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Ann-Katrin Inderthal Grant/research support from: Pfizer Pharma GmbH, Anna Knothe Grant/research support from: Pfizer Pharma GmbH, Klaus Frommer: None declared, Corinna Heck: None declared, Mona Arnold: None declared, Ingo Tarner: None declared, Walter Hermann: None declared, Carlos Francisco Meneses Villalba: None declared, Ulf Müller-Ladner: None declared, Rebecca Hasseli: None declared, Elena Neumann: None declared.